The present invention relates to an antitheft label for use on objects, such as goods, books, computer diskettes, etc. for preventing such objects from being stolen from, for example, stores and libraries. The invention also relates to an absorptive pad for use on food that has such an antitheft label attached thereto for preventing food items from being stolen.
In general, cases of shoplifting at department stores and supermarkets are increasing in number year by year. The reduction in the size of computer disks, for example, is said to be one of the reasons for the recent increase in the number of cases where disks containing important information are stolen or taken without permission. To avoid this trouble, namely, for antitheft purposes, an antitheft label in the form of a soft magnetic metal strip is attached to an object, and is used together with a magnetic system that detects a change in magnetic field. Typically, the magnetic system is installed at the exit of the store or the place of storage in order to detect when an object is removed, thereby keeping an eye on the goods.
Antitheft labels for use in such magnetic detection systems include marks as described in "Amorphous Antitheft Marks" (U.S. Pat. No. 4,484,184 and U.S. Pat. No. Re. 32428) and goods surveillance markers as described in "Marker for Electronic Surveillance System and Electronic Goods Surveillance System To Be Operated with Such Marker" (U.S. Pat. Nos. 4,660,025, 4,686,516, and 4,797,658).
An absorptive pad is conventionally used on food in order to absorb fluids which ooze from the food, for example, gravy and blood that drip from animal and fish meat. An example of a prior art absorptive pad for use on food is shown in FIG. 3. The absorptive pad as generally indicated by reference numeral 10 includes a short-fiber pulp sheet 8 that is sandwiched between an upper tape 6 and a lower tape 7, each of the tapes being formed of a polyethylene film. A plurality of holes 9 are formed in the lower tape 7 so that the gravy or blood from the food product is guided towards the pulp sheet 8. The absorptive pad 10 having this construction is usually placed in contact with the food at the bottom of the food tray.
A problem with such prior art antitheft labels is that the labels are visible and accessible to customers as the labels are usually attached to the outer side of the object. Thus, if one intends to steal an object, he needs only to select the object to which the antitheft label is not attached or from which the label has come off. Alternatively, the label can be deliberately removed from the item so that the object can be stolen without detection.
To solve these and other problems with the prior art, the antitheft label is attached to the inner side of the package of objects so that the label is not accessible to or seen from the outside.
Nevertheless, this practice causes other problems. For instance, frozen or cooked food sold on today's market is ready to eat by simply thawing or heating the food in the package in which it was purchased in a high-frequency heater, such as a microwave oven. However, during heating, spark discharge occurs at edges of the soft magnetic metal strip forming the antitheft label, thereby causing fire damage to the food.
If the antitheft label and the animal/fish meat, perishable food, or other food products which are to be protected from shoplifting are contained within the same package to insure that the label will not be accessible to and visible from the outside, then the direct or indirect contact between the label and the food item will cause problems relating with food sanitation.
Further, placing the label inside of the package requires much labor and time on the part of the stores in that the antitheft labels must be attached to each of the containers or packages. Hence, it is desired to have a system in which the stores need only place the goods in a package which already has an antitheft label provided therein.